Definitely my current 135. Almost hoping they can't ever fix it so I can lemon the damned thing. As far as my family goes we had an 04 745i that kept loosening its chassis bolts, sold it after four months of dreadful ownership. Our 06 Jeep Grand Cherokee isn't far behind, its in the shop every 5k with something electrical.
Most reliable of mine so far has been my 06 Range Rover believe it or not. It had a few small stupid things that bothered me that the dealer couldn't fix but other than that it was perfect.
Most reliable in the family was an E65 750i and our current E39 M5. We also had an E39 530i that was perfect from new to 85000 miles when we had an alternator and a water pump go in the same month, got rid of it after that.
2012 991 C2S
Still have BMW's in the family:
2003 E39 M5, 2009 F01 750i, 2010 E92 335i